Zafirlukast is a synthetic, selective peptide
leukotriene receptor
antagonist (LTRA), with the chemical
name 4-(5-cyclopentyloxy-carbonylamino-1-methyl-indol-3-ylmethyl)-3-methoxy-N-o-tolylsulfonylbenzamide.
The molecular weight
of zafirlukast is 575.7.

The empirical formula
is C31H33N306S.

Zafirlukast, a fine white
to pale yellow amorphous
powder, is practically insoluble in water. It is slightly soluble
in methanol and freely
soluble in tetrahydrofuran, dimethylsulfoxide, and acetone.